[DeTomaso] Update - cause of death - blown engine

Asa Jay Laughton asajay at asajay.com
Sun Jan 10 23:47:34 EST 2010 

The brand of torque wrench isn't necessarily the key.  The key is making 
sure it's calibrated.  I'm sure your local Snap-On dealer can help you 
with that though.

I've only done a handful of engines myself.  My first ones were during 
the time I spend earning my Automotive Technologies degree.  I don't 
remember what sparked it, probably something that had happened to other 
classmates, I can't be sure.  On every engine I've built, I never button 
it up the same day I torque it.  I go through all the proper torque 
procedures, then walk away.  The next day I come back and check the 
torque on all the bolts.  After a couple days of that as I perform other 
stuff, I put the pan on.

That's still no guarantee something won't break.  However in my own 
mind, it allows me opportunity to make sure it's right -and- make sure 
nobody else messed with it.

The other thing I do is duct tape all the ports, exhaust ports, intake 
ports, manifold etc.  One of the first engines in our class promptly 
bent a valve and punched a nice hexagon shaped hole in the top of a 
piston.  Somehow, the partners on that one had managed to drop a nut 
down the cylinder.  So my partner and I did a quick inspection, then 
taped all the ports shut.

:)
Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired

& Shelley Marie
Spokane, WA

1971 Mach I Mustang  [ASA JAY]
1973 Pantera L 5533  [ASASCAT]
    
******************************     
http://www.asajay.com
http://www.teampanteraracing.com
  



Will Kooiman wrote:
> The bummer is I know I torqued the rods.  I even used a rod stretch gauge to
> measure the stretch - just for grins.  I can't explain, however, why it only
> took 40-50 lb/ft to loosen the bolts.
>
> Also - I'm definitely not a professional, but I've put together several
> engines - maybe 10 or 15.  This is the first time anything like this has
> happened.
>
> I'm going to put the next one together too, but this time I'm going to make
> damn sure the torque is correct on all of the critical bolts.
>
> I'm also going to buy a better torque wrench - probably snap-on.
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
> Behalf Of Asa Jay Laughton
> Sent: Sunday, January 10, 2010 9:23 PM
> To: 'De Tomaso List'
> Subject: Re: [DeTomaso] Update - cause of death - blown engine
>
> wow
>
>
>
>
> Asa Jay
>
> Asa Jay Laughton, MSgt, USAFR, Retired
>
> & Shelley Marie
> Spokane, WA
>
> 1971 Mach I Mustang  [ASA JAY]
> 1973 Pantera L 5533  [ASASCAT]
>     
> ******************************     
> http://www.asajay.com
> http://www.teampanteraracing.com
>   
>
>
>
> Will Kooiman wrote:
>   
>> I pulled my engine today.  I haven't taken it completely apart, but I
>>     
> pulled
>   
>> the pan.
>>
>>  
>>
>> The official cause of death is:      The #4 rod cap came off.  It appears
>> that the rod bolts were not properly torqued.
>>
>>  
>>
>> Here's what I found inside the pan:
>>
>>  
>>
>> The #4 rod cap was not attached to the crank.  A rod bolt was in the pan.
>> I'm sure the other rod bolt is in the pan somewhere, but I haven't found
>>     
> it
>   
>> (haven't looked through the sludge).
>>
>>  
>>
>> The #4 rod cap was in one piece in the pan.  It was flattened out.
>>
>>  
>>
>> I found the #4 rod bearing.  It is still in a half circle.  I haven't
>> examined it very much.  It was getting dark, and I had to do chores.
>>
>>  
>>
>> The #8 rod is broken in half.  The cap is still on the crank.  I
>>     
> previously
>   
>> thought it was the #4 rod that was broken.  I couldn't tell for sure
>>     
> because
>   
>> I was looking down the #4 bore -- which had the #4 piston lodged sideways
>>     
> in
>   
>> it.
>>
>>  
>>
>> The #8 piston has the pin broken out of the piston.  At first I thought
>>     
> the
>   
>> piston came apart to cause the destruction, but it looks like the crank
>> counterweights cut it off after the rod broke and the piston dropped into
>> the crank.  The counterweights have some debris on the leading edge to
>> support this theory.
>>
>>  
>>
>> The #4 main cap (between #3/7 and #4/8) is cracked at the base.
>>
>>  
>>
>> The #4 cylinder is cracked.  I think this happened when the #4 piston went
>> sideways.  I don't know about #8.  I haven't removed the driver's cylinder
>> head.
>>
>>  
>>
>> The #4 rod journal is gouged slightly on one side.  It looks like it got
>>     
> hit
>   
>> after the rod came off.  If the bearing had spun, it would have cut
>>     
> grooves
>   
>> along the entire circumference.  I think the crank is going to be
>>     
> reusable.
>   
>>  
>>
>> I just bought a new torque wrench -- in case my old wrench was inaccurate.
>>     
> I
>   
>> checked the #8 rod.  It was only torqued to 40 lb/ft.  It is supposed to
>>     
> be
>   
>> torqued to 67.  I checked a few of the other rods, and they were in the
>> 40-50 range too.
>>
>>  
>>
>> I checked a couple of the inner mains (ARP studs).  They were around 120
>> lb/ft.
>>
>>  
>>
>> I don't think the torque wrench is bad, otherwise the mains would be off
>> too.  The inner head bolts were correct too.  The outer head bolts have
>> always lost torque due to the excessive heat compressing the aluminum.
>>
>>  
>>
>> I'm guessing that either
>>
>>  
>>
>> a)       I set the torque wrench incorrectly when I did the rods or
>>
>> b)       I didn't use the proper procedure to torque the rods or
>>
>> c)       Both.
>>
>>  
>>
>> I did not torque it, loosen it, torque it, loosen it, torque it.  I used
>>     
> the
>   
>> grey moly grease that came with the rods on the threads and under the bolt
>> heads.  I snugged them up with a ratchet, and then I torqued them to about
>> 35 (don't remember -- I usually go about ½ of the final torque), and then
>>     
> I
>   
>> torqued them to 67.  I measured the bolt length before and after they were
>> torqued.  I didn't write it down, but I'm pretty sure they stretched
>>     
> 0.004".
>   
>>  
>>
>> The block is probably reusable with a sleeve, a new #4 main, and a line
>> bore.  It will probably cost more than it's worth, though. The crank might
>> be reusable.  The #4 and #8 pistons are obviously trash as are the #4 and
>>     
> #8
>   
>> rods.  Everything else looks like it's in good shape.
>>
>>  
>>
>> I'll do pictures eventually.  It's going to be at least 2 weeks, though.
>>     
> I
>   
>> have a lot of non-car-stuff going on -- going out of town next weekend.
>>
>>  
>>
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